Soil respiration of alpine meadow is controlled by freeze–thaw processes of active layer in the permafrost region of the Qinghai–Tibet Plateau

Wang, Junfeng; Wu, Qingbai; Yuan, Ziqiang; Kang, Hojeong

Freezing and thawing action of the active layer plays a significant role in soil respiration (inline-formulaRs) in permafrost regions. However, little is known about how the freeze–thaw processes affect the inline-formulaRs dynamics in different stages of the alpine meadow underlain by permafrost in the Qinghai–Tibet Plateau (QTP). We conducted continuous in situ measurements of inline-formulaRs and freeze–thaw processes of the active layer at an alpine meadow site in the Beiluhe permafrost region of the QTP and divided the freeze–thaw processes into four different stages in a complete freeze–thaw cycle, comprising the summer thawing (ST) stage, autumn freezing (AF) stage, winter cooling (WC) stage, and spring warming (SW) stage. We found that the freeze–thaw processes have various effects on the inline-formulaRs dynamics in different freeze–thaw stages. The mean inline-formulaRs ranged from 0.12 to 3.18 inline-formulaµmol minline-formula−2 sinline-formula−1 across the stages, with the lowest value in WC and highest value in ST. inline-formulaQ10 among the different freeze–thaw stages changed greatly, with the maximum (inline-formula4.91±0.35) in WC and minimum (inline-formula0.33±0.21) in AF. Patterns of inline-formulaRs among the ST, AF, WC, and SW stages differed, and the corresponding contribution percentages of cumulative inline-formulaRs to total inline-formulaRs of a complete freeze–thaw cycle (inline-formula1692.98±51.43 g inline-formulaCO2 minline-formula−2) were inline-formula61.32±0.32 %, inline-formula8.89±0.18 %, inline-formula18.43±0.11 %, and inline-formula11.29±0.11 %, respectively. Soil temperature (inline-formulaTs) was the most important driver of inline-formulaRs regardless of soil water status in all stages. Our results suggest that as climate change and permafrost degradation continue, great changes in freeze–thaw process patterns may trigger more inline-formulaRs emissions from this ecosystem because of a prolonged ST stage.

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Wang, Junfeng / Wu, Qingbai / Yuan, Ziqiang / et al: Soil respiration of alpine meadow is controlled by freeze–thaw processes of active layer in the permafrost region of the Qinghai–Tibet Plateau. 2020. Copernicus Publications.

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